This invention is generally in the field of extracting and using waste heat from some heat source, such as an internal combustion engine hot exhaust pipe or the hot stack of some manufacturing plant, to provide power for air conditioning some enclosed space. The invention is specifically comprised of a system wherein heat is extracted from the hot exhaust or stack and is used as a heat source for the hot volume in the hot cylinder of a Vuilleumier refrigerator, i.e. a thermal compressor air conditioner.
One main advantage of the present invention over prior art air conditioning devices using mechanical power from the internal combustion engine or electrical power from an engine driven generator is that the only power used is the waste heat and some rotational input device, such as an automobile belt driven shaft, having a small amount of mechanical power that is sufficient to overcome friction in driving the hot displacer containing a regenerator matrix therein.
The system of the present invention, therefore, has the hot volume at one end of a hot-side cylinder and a rotational input device that reciprocally moves the hot displacer within the hot-side cylinder as explained above. The rotational input device drives a crankshaft in a crankcase volume opposite the hot volume wherein a displacer rod is mechanically connected between an outer point, such as an impulse plate, on the crankshaft and the displacer. A hollow pressure line is connected between the crankcase volume and a plurality of free-displacer regenerator matrix refrigerators in a cold finger array. The amount of the crankcase volume is minimized for better efficiency in providing alternating pressure waves through the hollow pressure lines to the plurality of free-displacer refrigerators. The high portion of the pressure wave in the pressure line is when the displacer is the farthest into the crankcase volume because there is more hot volume at this time. Conversely, the low portion of the pressure wave occurs after the displacer has moved by the up stroke to the farthest point into the hot volume thus extracting heat from the hot volume during the up stroke and establishing a cooler temperature of the fluid medium, and thus a lesser pressure, now in the pressure line.
These alternating high and low pressure waves are applied to a plurality of free-displacer regenerator matrix refrigerators within a cold finger matrix as is explained herein below. The hot ends and the cold ends of the cold finger matrix are insulated from each other and are in separate hot and cold air ducts respectively so that heat removed from the vicinity of the cold ends is swept out the hot air duct. The average pressure in the pneumatic volumes of the free-displacer refrigerators is about equal to the average pressure in the working volume caused by the alternating pressure waves from the Vuilleumier compressor. However, as the working fluid pressure in the working volume, which is common to all of the free-displacer refrigerators, increases past the average in the pneumatic volume sufficient to move the free-displacers, the free-displacers move toward the ambient volume. The resultant expansion of the cold volumes at the cold ends at high working fluid pressure produces cooling in the cold volumes and an equal amount of heating in the ambient volumes. The low working fluid pressure half of the pressure waves from the Vuilleumier compressor creates a lower pressure than the average causing motion of the free displacer away from the pneumatic volume. The cold volume is, therefore, decreased and thus heated, but to a lesser amount than the heat removed during the expansion cycle. The result is net cooling of all the cold volumes. The cold volumes produce cooling in the cold air duct. Air circulated through the cold air duct by the fan may guide the cooled, air conditioned air to the desired inclosed space.